Display device and display optical system unit

ABSTRACT

A display apparatus includes a light source, and a partition wall which divides an inside of the display apparatus into an enclosing space which includes a plurality of optical elements and an outer space with respect to the enclosing space. The optical elements includes a color separator which receives a light from the light source and emits a plurality of separate color beams, at least one reflecting type light valve which forms an image by reflecting the plurality of color beams, and a projection lens which projects the image of an external screen. A first cooling fan is provided which causes an air flow in the outer space. A least one of the optical elements forms a part of the partition wall, and the air flow cools the at least one reflecting type light valve from the outer space.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 11/181,927, filedJul. 15, 2005, now U.S. Pat. No. 7,128,422, which is a continuation ofU.S. application Ser. No. 10/919,288, filed Aug. 17, 2004, now U.S. Pat.No. 6,935,750, which is a continuation of U.S. application Ser. No.10/463,573, filed Jun. 18, 2003, now U.S. Pat. No. 6,779,894, which is acontinuation of U.S. application Ser. No. 10/140,122, filed on May 8,2002, now U.S. Pat. No. 6,582,083, which is a continuation of U.S.application Ser. No. 09/446,336, filed Dec. 20, 1999, now U.S. Pat. No.6,394,608, which is a 371 of PCT/JP98/02740, filed Jun. 19, 1998, thesubject matter of which is incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a display device, such as a liquidcrystal projector device, a liquid crystal television set, and aprojection type display device or the like, which projects a video imageon a screen by utilizing a light valve device, such as a liquid crystalpanel.

BACKGROUND OF THE INVENTION

There is a projection type display device, such as a liquid crystalprojector, which changes light from a light source, such as an electricbulb, to a contrast per pixel image using a light valve device, such asa liquid crystal panel, and projects an enlarged image on a screen orthe like. Further, as the light valve device of the display device,devices of two operation types, a light transmitting type light valvedevice and a reflecting type light valve device, are known.

The light valve device generally comprises a semiconductor drivingdevice and an optical function material such as liquid crystal or thelike. To normally operate both constituents, a predetermined temperature(e.g., 60° C.) or lower must be maintained in the device. On the otherhand, light from the light source, except for light that is to befinally projected, is absorbed by the light valve device and itsperipheral optical elements and the like, and this light turns to heat.Accordingly, in a projection type video display device, the light valvedevice must be cooled so as not to overheat beyond a range of normaloperation. The significance of cooling is becoming more and moreimportant with an increase in the intensity of the light-source lightfor recent high-brightness projection video images, since the increasein the light-source light intensity increases the amount of heatgeneration which occurs in the light valve device.

Further, in such a display device, as the optical system brings thelight of the image from the light valve device into focus, images offoreign particles, such as dust attached around the light valve device,are enlarged and projected on the screen or the like. Accordingly,prevention of dust around the light valve device is also an importantproblem to be solved.

Conventionally, a display device using a reflecting type light valvedevice is disclosed in Japanese Published Unexamined Patent ApplicationNo. Sho 64-5174. Further, a technique to cool the reflecting type lightvalve device in a display device is disclosed in Japanese PublishedUnexamined Patent Application No. Sho 62-294230. According to thistechnique, a cooling device is provided on the rear of a liquid crystalpanel operating as the reflecting type light valve device.

Further, a technique to prevent dust in the display device is disclosedin Japanese Published Unexamined Patent Application, No. Hei 7-152009.According to this technique, a liquid crystal panel operating as a lighttransmitting type light valve device is placed within an enclosed space,and air within the enclosed space is circulated to radiate heatgenerated by the liquid crystal panel and transmit the heat to theoutside of the enclosed space.

In the device disclosed in Japanese Published Unexamined PatentApplication No. Sho 64-SI74, the cooling of the light valve device anddust prevention around the light valve device are not considered, andthe disturbance of normal operation due to the above-describedoverheating and the occurrence of shadows on the screen due to dust havenot been fully considered.

Further, in the technique disclosed in Japanese Published UnexaminedPatent Application No. Sho 62-294230, the prevention of dust around thelight valve device is not considered, and the occurrence of shadows onthe screen due to dust has not been fully considered.

Further, in the technique disclosed in Japanese Published UnexaminedPatent Application No. Hei 7-152009, since the cooling is performed viathe air present within the enclosed space, efficient cooling cannot beexpected. Further, in a case where the amount of heating increases dueto an increase in the light-source light intensity, the light valvedevice might not be sufficiently cooled. In this case, the displaydevice cannot be normally operated, and this problem has not been fullyconsidered.

Accordingly, the present invention has an object to provide a projectiontype display device which efficiently performs dust prevention aroundthe light valve device and cooling of a light valve device.

SUMMARY OF THE INVENTION

To attain the foregoing object, the present invention provides variousfeatures.

As a first feature, there is provided a display device which performsimage display based on light reflected from a reflecting type lightvalve means, wherein said reflecting type light valve means is providedin a partition wall forming an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans, in a state where at least a part opposite to a lightincidence/emission surface of said light valve means is connected tocooling means disposed outside said enclosed space.

As a second feature, there is provided a display device which performsimage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is set on the sideof said enclosed space, and wherein a part opposite to said lightincidence/emission surface is connected to cooling means.

As a third feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a transparentmember is provided on a light incidence/emission surface of said lightvalve means, and a part opposite to said light incidence/emissionsurface is connected to cooling means outside said enclosed space.

As a fourth feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is on the side ofsaid enclosed space, and wherein a radiation member is connected to apart opposite to said light incidence/emission surface such that saidradiation member is cooled by a cooling member.

As a fifth feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, and cooling means, disposed outsidesaid enclosed space, for cooling at least said partition wall, whereinsaid reflecting type light valve means is provided within said enclosedspace, and wherein a part opposite to a light incidence/ emissionsurface of said light valve means is connected to said partition wall,whereby said reflecting type light valve means is cooled by said coolingmeans via said partition wall.

As a sixth feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, wherein said reflecting type light valve means is providedin a partition wall forming an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans.

As a seventh feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a lightincidence/emission surface of said light valve means is on the side ofsaid enclosed space, and a part opposite to said lightincidence/emission surface is outside said enclosed space.

As an eighth feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means, wherein said reflecting type lightvalve means is provided in said partition wall such that a transparentmember is provided on a light incidence/ emission surface of said lightvalve means and a part opposite to said light incidence/emission surfaceis outside said enclosed space.

As a ninth feature, a display device is provided which receives lightfrom a light source into a reflecting type light valve means andgenerates an image display based on reflected light, comprising: apartition wall that forms an enclosed space including at least anincidence/emission optical system of said reflecting type light valvemeans, wherein said reflecting type light valve means is provided insaid partition wall such that a light incidence/emission surface of saidlight valve means is on the side of said enclosed space, and wherein aradiation member is connected to a part opposite to said lightincidence/emission surface.

As a tenth feature, a display device is provided which generates animage display based on light reflected from a reflecting type lightvalve means, comprising: a partition wall that forms an enclosed spaceincluding at least an incidence/emission optical system of saidreflecting type light valve means and that has thermal conductivity,wherein said reflecting type light valve means is provided in saidenclosed space, and wherein a part opposite to a lightincidence/emission surface of said light valve means is connected tosaid partition wall.

As an eleventh feature, a display optical system unit is provided whichreceives light from a light source into a reflecting type light valvemeans, then passes reflected light through a projection lens, and formsimage display projection light, comprising: a partition wall that formsan enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means, wherein saidreflecting type light valve means is provided in said partition wall ina state where a part opposite to a light incidence/emission surface ofsaid light valve means is connected to cooling means outside saidenclosed space.

As a twelfth feature, a display optical system unit is provided whichreceives light from a light source into reflecting type light valvemeans, then passes reflected light through a projection lens, and formsimage display projection light, comprising: a partition wall that formsan enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means, wherein saidreflecting type light valve means is provided in said partition wall ina state where a transparent member is provided on a lightincidence/emission surface of said light valve means.

As a thirteenth feature, a display optical system unit is provided whichreceives light from a light source into reflecting type light valvemeans, then passes reflection light through a projection lens, and formsimage display projection light, comprising: a partition wall that formsan enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means, wherein saidreflecting type light valve means is provided in said partition wall ina state where a light incidence/emission surface of said light valvemeans is on the side of said enclosed space, and a radiation member isconnected to a part opposite to said light incidence/emission surfacesuch that said radiation member is cooled by cooling means.

As a fourteenth feature, a display optical system unit is provided whichreceives light from a light source into reflecting type light valvemeans, then passes reflection light through a projection lens, and formsimage display projection light, comprising: a partition wall that formsan enclosed space including at least an incidence/emission opticalsystem of said reflecting type light valve means and that has thermalconductivity, wherein said reflecting type light valve means is providedin said enclosed space, and wherein a part opposite to a lightincidence/emission surface of said light valve means is connected tosaid partition wall, whereby said reflecting type light valve means canbe cooled by external cooling means via said partition wall.

According to the above constructions, the occurrence of shadows in aprojection image due to dust can be prevented. Further, radiation andcooling on the reflecting type light valve means can be efficientlyperformed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the external appearance of adisplay device according to a first embodiment of the present invention;

FIG. 2 is a perspective view showing the internal structure of thedisplay device according to the first embodiment of the presentinvention;

FIG. 3 is a perspective view showing the internal structure of anoptical chassis of the display device according to the first embodimentof the present invention;

FIG. 4 is a cross sectional view showing the structure of the displaydevice according to the first embodiment of the present invention;

FIG. 5 is a cross sectional view showing the structure of the displaydevice according to a second embodiment of the present invention;

FIG. 6 is a cross sectional view showing the structure of the displaydevice according to a third embodiment of the present invention;

FIG. 7 is a cross sectional view showing the structure of the displaydevice according to a fourth embodiment of the present invention;

FIG. 8 is an expanded cross sectional view showing a liquid crystalpanel attachment portion of the display device according to the fourthembodiment of the present invention;

FIG. 9 is a cross sectional view showing the structure of the displaydevice according to a fifth embodiment of the present invention;

FIG. 10 is a cross sectional view showing the structure of the displaydevice according to a sixth embodiment of the present invention;

FIG. 11 is a cross sectional view showing the structure of the displaydevice according to a seventh embodiment of the present invention; and

FIG. 12 is a cross sectional view showing the structure of the displaydevice according to an eighth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in detail withreference to the accompanying drawings.

A first embodiment of the present invention will be described withreference to FIGS. 1 to 4.

FIG. 1 shows the external appearance of a display device. In a displaydevice 1 shown in FIG. 1, a part of a projection lens 4 is exposedoutside an outer casing of the display device. A video image isprojected on an external screen or the like from the projection lens 4.Further, an outlet port 14 is provided in the front side, and an inletport 11 is provided near the rear side. External air is taken from theinlet port 11 and is used for cooling the inside the device, then theheated air is discharged from the outlet port 14 to the outside of thedevice.

FIG. 2 shows the display device of FIG. 1 as seen when a side cover ofthe device is removed. As shown in FIG. 2, a video display mechanism isprovided in the display device 1. The video display mechanism comprisesan optical chassis 15 sealed by a cover 16 and light source members 21to 23. The details of the respective parts shown in FIG. 2 will bedescribed later with reference to FIG. 4.

FIG. 3 shows the structure of FIG. 2 as seen when the cover 16 of theoptical chassis 15 is removed. The inside of the optical chassis 15comprises a space 5 which is sealed from the outside to prevent dustfrom entering by attachment of the cover 16. In the followingdescription of the embodiment, this space 5 will be referred to as an“enclosed space” and the sealed chassis 15 will be referred to as an“enclosure” .

Hereinbelow, the respective parts will be described in detail withreference to FIG. 4, which represents a cross section of the displaydevice 1 in this status.

As shown in FIG. 4, a video display mechanism is provided in the displaydevice 1. The video display mechanism comprises the optical chassis 15and a light source portion. Light emitted from the light source portionis reflected by a light-polarizing type reflection liquid crystal panel3, operating as a reflecting type light valve, and the reflected lightis directed toward the outside of the device 1 via the projection lens4, where the light is projected on a screen (not shown). The lightsource portion includes an electric bulb 2, a reflector 21 and condenserlenses 22 and 23. Light from the electric bulb 2 is collected by thereflector 21, is formed into an approximately collimated light beam viacondenser lenses 22 and 23, and passes into the optical chassis 15.

The light from the condenser lens 23 passes through an incidence coverglass 24 made of transparent material into the optical chassis 15. Theincidence cover glass 24 is provided as a part of a partition wall toseal the inside of the optical chassis 15. The light which has enteredthe optical chassis 15 passes through a cover glass 33 provided in frontof the liquid crystal panel 3, and is reflected by the liquid crystalpanel 3, which operates as a reflecting type light valve device. Thecover glass 33 is provided as a part of the partition wall to seal theinside of the optical chassis 15. The liquid crystal panel 3 is in tightcontact with the cover glass 33, so that no extraneous gas entersbetween the cover glass 33 and the liquid crystal panel 3.

The light reflected by the liquid crystal panel 3 again passes throughthe cover glass 33, then, passes through the projection lens 4, and isprojected toward the outside. The projection lens 4 is also provided asa part of the partition wall of the optical chassis 15 to seal theinside of the optical chassis 15.

In the entire optical system, among the optical axes, a section from theincidence cover glass 24 to the cover glass 33 and a section from thecover glass 33 to the projection lens 4 are disposed inside the enclosedspace 5 and are sealed from the outside. On the optical axes, the frontand rear of the liquid crystal panel 3 are in enclosed spaces;therefore, dust or the like cannot enter from the outside. Accordingly,when an image displayed on the liquid crystal panel 3 is projected andthe focal point of the projection lens 4 is adjusted to obtain a sharpimage from the liquid crystal panel 3, since the liquid crystal panel 3and its peripheral portion are in an enclosed space, dust or the likecan not collect around the focal point and so no shadow occurs in theprojected video image.

The liquid crystal panel 3 comprises a two-dimensionally arranged matrixof liquid crystal cells corresponding to two-dimensionally arrangedpixels (e.g., 1024 pixels in a horizontal direction and 768 pixels in avertical direction, i.e., total 786432 pixels) for forming an image. Theliquid crystal panel controls whether light is reflected or absorbed bythe liquid crystal panel 3, per pixel, by selectively controlling theON/OFF state of each liquid crystal cell based on an image signalsupplied from an image display circuit (not shown), whereby an image isdisplayed. For example, for a liquid crystal panel in which light isreflected when the liquid crystal is in the off state, and light isabsorbed when the liquid crystal is in the on state, a pixelcorresponding to a bright part of an image is turned off, while a pixelcorresponding to a dark part is turned on. In this manner, reflectionand absorption is selectively controlled for respective pixels whichform a two dimensional video image, and an image is displayed on thetwo-dimensional surface of the liquid crystal panel 3. Then, the imageformed on the surface of the liquid crystal panel 3 is projected as anenlarged image on the external screen (not shown) by the projection lens4.

The liquid crystal panel 3 reflects or absorbs incident light inaccordance with the contents of an image to be displayed. The absorbedlight becomes thermal energy and raises the temperature of the liquidcrystal panel. Further, even when light is reflected, all the light isnot reflected, but a part of the light is absorbed into the liquidcrystal panel 3 and becomes thermal energy. When the generated thermalenergy is at a maximum level, the entire content of the image is black,for example, and almost all the incident light is absorbed. That is, tooperate the liquid crystal panel within its operational temperaturerange, radiation corresponding to the energy generated in the panel mustbe provided.

In the present embodiment, thermal energy generated in the liquidcrystal panel 3 is radiated and cooled by cooling means provided on aradiation surface on the rear side of the liquid crystal panel 3. Thatis, a radiation fin 31 is attached to the rear surface of the liquidcrystal panel 3, and the heat generated in the liquid crystal panel 3 istransmitted to the radiation fin. The radiation fin 31 is cooled by anair flow from a radiation fan 6. The radiation fan 6 is supplied withoutside air sucked into the inlet port 11. Thus, the radiation fin 31 iscooled with air having a temperature which is always close to that ofthe outside air.

For cooling the entire display device 1, the outside air is sucked intothe inlet port 11 by a cooling fan 7 and is discharged from the outletport 14. The outside air is always supplied around the radiation fan 6and the radiation fin 31 to provide cooling for the rear of the panel.

Further, the air used for cooling around the liquid crystal panel isalso used for cooling around the electric bulb 2, i.e., the reflector 21and the condenser lenses 22 and 23, and is discharged by the fan 7 fromthe outlet port 14 to the outside the device 1. By this arrangement, theheat generated in the device can be effectively discharged to theoutside the device.

In this manner, in the first embodiment, parts related to the opticalsystem of the liquid crystal panel 3 are sealed in an enclosed space,and heat generated in the enclosed space is sent to the outside theenclosed space and radiated away. This attains both advantages ofprevention of dust on the side of the incidence/emission surface of theliquid crystal panel and prevention of a temperature rise.

Hereinbelow, a second embodiment of the present invention will bedescribed. FIG. 5 shows the structure of the display device 1 accordingto the second embodiment. FIG. 5 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

The difference between this embodiment and the first embodiment shown inFIG. 4 is that, in the present embodiment, the liquid crystal panel 3,operating as a reflecting type light valve means, is directly providedin the wall of the enclosed space 5, so that the liquid crystal panel 3forms part of the partition wall of the optical chassis 15. Theradiation surface on the rear of the liquid crystal panel 3 facesoutwardly from the partition wall of the enclosed space 5, and theradiation fin 31 serving as part of the cooling means is attached there.Further, the image display surface of the liquid crystal panel 3 whereincidence/emission of light occurs is within the enclosed space. Withthis arrangement, in addition to the advantages of the first embodiment,the cover glass which forms a window in the partition wall member isunnecessary, which simplifies the structure of the device.

Hereinbelow, a third embodiment of the present invention will bedescribed. FIG. 6 shows the structure of the display device 1 accordingto the third embodiment. FIG. 6 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

The difference between the third embodiment and the first embodimentshown in FIG. 4 is that, in the present embodiment, the entire liquidcrystal panel 3, operating as a reflecting type light valve means, isdisposed within the enclosed space of the optical chassis 15, and theradiation fin 31, which forms a part of the radiation means connected tothe radiation surface on the rear of the liquid crystal panel 3, servesas part of the partition wall of the optical chassis 15. In thisarrangement, as in the case of the second embodiment, the structure ofthe device can be further simplified in comparison with the firstembodiment.

Hereinbelow, a fourth embodiment of the present invention will bedescribed. FIG. 7 shows the construction of the display device 1according to the fourth embodiment. FIG. 7 shows a cross section of thedisplay device 1 as in the case of FIG. 4.

The difference between the first embodiment shown in FIG. 4 is that, inthe present embodiment, the liquid crystal panel 3, operating as areflecting type light valve means, is connected to the partition wall ofthe optical chassis 15 forming the enclosed space 5 via a flexiblebellows 34 in the present embodiment, as shown in FIG. 8, whichrepresents an enlarged view of the liquid crystal panel 3 and thebellows 34, the bellows 34 and the liquid crystal panel 3 form a part ofthe partition wall of the enclosed space 5.

In some cases, the attachment position of the liquid crystal panel 3must be adjusted to a predetermined reflection angle and position so asto correctly project a video image. In such case, according to thepresent embodiment, since the bellows 34 is provided between the wallforming the enclosed space of the optical chassis 15 and the liquidcrystal panel 3, even if the attachment position of the liquid crystalpanel 3 is moved, the flexible bellows 34, in a distorted state, willmaintain the integrity of the enclosed space.

In this manner, the adjustment is simple, and upon adjustment, theentrance of dust into the optical chassis can be prevented.

Hereinbelow, a fifth embodiment of the present invention will bedescribed. FIG. 9 shows the structure of the display device according tothe fifth embodiment. FIG. 9 shows a cross section of the display device1 as in the case of FIG. 4.

The fifth embodiment is capable of producing a color video imageprojection by providing three reflecting type light valve means,corresponding to the three primary colors of a video image, andproviding light separation/combining means for use with respect to thethree primary colors in the optical path.

In this display device, light generated from the electric bulb 2 becomesapproximately collimated light, via the reflector 21 and the condenserlenses 22 and 23, and passes into the enclosed space 5 of the opticalchassis 15 via the incidence cover glass 24. In the enclosed space 5, adichroic mirror 36 and a dichroic mirror 35 are provided, respectively,for reflecting a blue color component of light having, e.g., ahalf-value breadth range of 400-500 nm, a red color component of lighthaving, e.g., half-value breadth range of 600-700 nm, and for passingthe other light component. The blue color component of light isreflected by the dichroic mirror 36, and is directed toward a liquidcrystal panel 3B. The remaining green and red color components passthrough the dichroic mirror 35 and continue toward the next dichroicmirror 35. The red color component of light is reflected by the dichroicmirror 35 and is directed toward a liquid crystal panel 3R. Theremaining green color component of light having, e.g., a wavelengthrange of 500-600 nm passes through the dichroic mirror 35 and continuestoward the liquid crystal panel 3.

Lights reflected by the liquid crystal panels operating as reflectingtype light valve means, so that the green color component of light isreflected from the liquid crystal panel 3 and is directed toward thedichroic mirror 35. The red color component of light is reflected fromthe liquid crystal panel 3R and is directed toward the dichroic mirror35. The red color component of light is again reflected by the dichroicmirror 35, and is directed toward the projection lens 4. The red colorcomponent of light is combined with the green component of light whichagain passes through the dichroic mirror 35. Next, the blue colorcomponent of light is again reflected by the dichroic mirror 36 and isdirected toward the projection lens 4. At this time, the blue colorcomponent of light is combined with the green color component and redcolor component of light. In this manner, the light finally enters theprojection lens 4, and the light to be projected includes a combinationof the blue, green and red primary color components.

At this time, if the reflection angles, distances and parallelism andthe like at the three liquid crystal panels are shifted from each other,the combined image will experience a shift in the colors, and, finally,a video image having an undesirable color shift will be projected.

Accordingly, the positions of the liquid crystal panels are adjusted tocorrect any color shift. As in the case of the fourth embodiment, aflexible bellows is attached between the respective liquid crystalpanels and the wall of the optical unit 15, so that, even if theposition of the liquid crystal panel is adjusted, the bellows maintainsthe integrity of the enclosed space.

The liquid crystal panels for the three primary colors, which operate asreflecting type light valve means, display images of the respectivecolor components. The three liquid crystal panels are respectivelyprovided with cooling means similar to the previous embodiments.Radiation fin 31B is attached to the liquid crystal panel 3B for theblue color component, and a flow of air from a radiation fan 6B isdirected at the fin. Radiation fin 31R is attached to the liquid crystalpanel 3R for the red color component, and a flow of air from a radiationfan 6R is directed at the fin. Further, radiation fin 31 is attached tothe liquid crystal panel 3 for the green color component, and a flow ofair from the radiation fan 6 is directed at this fin. In this manner,respective cooling means are provided for the three color components.

Air flow from the inlet port 11 is supplied to the cooling means for thethree color components, and the air which is heated after thermalexchange is used for finally cooling the light source portion and thanis discharged by the discharge fan 7 from the outlet port 14 to theoutside the device 1.

In this manner, even in a color projection device using three panels forthe three color components, the liquid crystal panels can be disposed incommunication with the optical system within the enclosed space, as wellas with the cooling means provided outside of the enclosed space.Hereinbelow, a sixth embodiment of the present invention will bedescribed. FIG. 10 shows the structure of the display device accordingto the sixth embodiment. FIG. 10 shows a cross section of the displaydevice 1 as in the case of FIG. 4.

In the present embodiment, the enclosed space is disposed only aroundthe liquid crystal panel which operates as a reflecting type light valvemeans. This reduces the size of the enclosed space, and upon adjustmentof position at which the liquid crystal panel 3 is attached to the wallof the enclosed space, the entire enclosed space can be moved. Thus,adjustment can be easily made.

Hereinbelow, a seventh embodiment of the present invention will bedescribed. FIG. 11 shows a cross section of a video image displayapparatus according to the seventh embodiment. In this video imagedisplay apparatus, a display device having a construction similar to oneof the above-described first to sixth embodiments is employed to projecta video image on a screen 19 which forms part of the apparatus, ratherthan on an external screen or the like, as previously described.

In FIG. 11, the optical chassis 15 is attached inside of a rear-surfaceprojection type display device 1′. The inside of the optical chassis 15is similar to that shown in FIGS. 2 to 9. A video image projected fromthe projection lens 4 of the optical chassis 15 passes through a mirror17 and a mirror 18, and is projected onto a screen 19 so as to bedisplayed. Note that in FIG. 11, the light source is omitted.

In this manner, a display device is incorporated in a rear-surfaceprojection type display apparatus and, has similar advantages to thosedescribed with reference to the first to sixth embodiments.

Hereinbelow, an eighth embodiment of the present invention will bedescribed. FIG. 12 shows the structure of the display device accordingto the eighth embodiment. FIG. 12 shows a cross section of the displaydevice as in the case of FIG. 4.

The difference between this embodiment and the first embodiment shown inFIG. 4 is that, in the eighth embodiment, the liquid crystal panel 3,which operates as a reflecting type light valve means, is providedentirely within the enclosed space 5, and the radiation surface side ofthe panel on the rear surface thereof is directly in contact with thewall surface of the optical chassis 15. In this arrangement, the wallsurface of the optical chassis 15 can be used as a cooling means. Theliquid crystal panel 3 can be cooled by cooling the outside of theoptical chassis 15 by using the radiation fan 6 or the like. Note thatin this case, the wall of the optical chassis 15 is formed of a materialhaving a good thermal conductivity, such as a metal.

Various embodiments of the video image display device according to thepresent invention have been described above. Note that in the abovedescription, the light-polarizing light-reflecting liquid-crystal panelis used as a reflecting type light valve means, however, light valvedevices of other types, e.g., a reflecting type light valve means of thescattering light-reflecting liquid-crystal panel type, a micro-mirror(micro-mirror drive) type panel, a laser-liquid-crystal writingreflecting type panel and the like, can be employed, and similaradvantages can be obtained.

Further, in the above description, the optical system uses a dioptriclens, however, optical devices other than a dioptric lens, such as areflection mirror lens or a combination of a dioptric lens and areflection mirror lens may be used.

Further, if only the part of video image display mechanism (the part inthe external casing of the video display device) or the optical chassisis directly provided in a building or the like, the external part may beintegrated with the building, and similar advantages can be obtained.

Further, in the fourth embodiment described above, a member having abellows structure is used as a flexible member connecting the liquidcrystal panel to the optical chassis, however, any other flexiblemembers which do not allow dust to pass, such as sponge foam, may beemployed. In this case, similar advantages can be obtained. That is, inthe above embodiments, the enclosed space 5 may be employed as long asit is sealed against dust, and this does not pose any limitation on thescope of the present invention.

As described above, in the various embodiments, the side of theincidence/emission surface of a reflecting type light valve device isprovided in a space sealed (protected) against dust, and a radiationsurface on the rear surface side of the light value device is connectedto cooling means outside the enclosed space. This efficiently dissipatesheat generated in the reflecting type light valve means and prevents theentrance of dust from the outside into the enclosed space. Further, theattachment position of the light valve device can be adjusted withoutbreaking the seal of the enclosed space by connecting the light valvedevice to the optical chassis with a flexible member.

As described above, according to the present invention, a projectiontype display device which prevents dust from collecting around a lightvalve device and efficiently cools the light valve device can beprovided.

The display device according to the present invention is available as aliquid crystal projector device, a liquid crystal television set, aprojection type display device and the like, and the present inventionis especially applicable to efficient execution of dust preventionaround a light valve device and cooling with respect to the light valvedevice.

1. A display device comprising: a light source which emits light; areflecting type light valve which forms an image utilizing the lightfrom the light source; a projection lens which projects the image; apartition wall which encloses at least a part of an inside portion ofthe display device; and a fan which provides air flow at a positionoutside of the partition wall, wherein at least the reflecting typelight valve and the projection lens form parts of the partition wall;and wherein the fan is adapted to supply an air flow to a rear side ofthe reflecting type light valve.
 2. A display device according to claim1, further comprising: a radiation fin which is attached to the rearside of the reflecting type light valve.
 3. A display device accordingto claim 1, wherein the reflecting type light valve is a micro-mirrortype panel.
 4. A display device according to claim 1, wherein thereflecting type light valve is a liquid crystal display panel.